Electrostatically Actuated Two-Dimensional Optical Scanner Having a High Resonant Frequency Ratio of Fast/Slow Axes

Abstract

Two-dimensional resonant optical scanners actuated by vertical electrostatic combs with a unique electrical isolation structure have been developed. The isolation on the movable frame surrounding 1mm-diameter gimbal mirror is made by trenching the top silicon layer of an SOI wafer with leaving the thick bottom layers. Thanks to the large mass of the frame, the resonant frequencies range in 65.0-89.2Hz for the frame and in 11.9-36.8kHz for the mirror in a 4mm×4mm chip. The resultant frequency ratio of the fast/slow axes reaches over 500 and such a high frequency ratio is utilized to display QVGA image by raster scanning of a laser beam.